According to a first aspect of the invention, there is provided a wound dressing which includes
a first and a second absorbent layer, each absorbent layer being of a non-woven fabric of fibres, and each being able to absorb liquid; and
a screen comprising polyester and cotton fibres between, and bonded to, the two absorbent layers, so that the two absorbent layers and the screen form essentially a single, layered fabric body, the bonding between the first and second absorbent layers and the screen being brought about by a needle-punching process in which the punching density is about 1700-1900 punches per square cm.
By xe2x80x9cpunching densityxe2x80x9d is meant the number of times a needle perforates the absorbent layers and the screen per square cm in order to bond them together. This is typically conducted on a needleloom which has a needle board with about 30 000 needles and about 6 000 needles per linear meter, at a punching rate of about 300 punches per square cm.
Preferably, the bonding between the first and second absorbent layers may be brought about by a needle-punching process in which the punching density is about 1800 punches per square cm.
The fibres may be porous fibres.
The wound dressing may include at least one liquid permeable layer which is substantially non-adherent to human or animal tissue overlaying, and bonded to, at least one of the absorbent layers.
The wound dressing may include a further liquid permeable layer disposed such that the single, layered fabric body is sandwiched between the two liquid permeable layers.
Each absorbent layer may be of porous polyester fibres. The screen may comprise 80% polyester and 20% cotton fibres. It may have a thread density of about 120 to 150 threads per square inch. It may have a yarn count of about 32 to 40. It may have a weight per unit area of approximately 100 g/m2.
The absorbent layers of non-woven fabric may be in the form of two fibre batts fabricated on a needleloom, each being made of 100% polyester fibre. The fibre batts may have a fineness of about 1.5 denier and a fibre length of about 7-8 cm, preferably about 7,62 cm (i.e. about 3 inches). They may have a weight per unit area of approximately 300 g/m2.
The single, layered fabric body may have a mass of about 700-750 g/m2. It may have a thickness of not more than about 3 mm.
The liquid permeable layer may be of a foraminous or perforated synthetic polymeric material. The synthetic polymeric material may be selected from xe2x80x9cMYLARxe2x80x9d (trade name) and xe2x80x9cTELFAxe2x80x9d (trade name).
The bonding between the or each liquid permeable layer and the or each absorbent layer may be achieved by heat treatment under pressure.
According to another aspect of the invention there is provided a method of making a wound dressing, the method including the steps of
fabricating two needle-punched fibre bans of fibres on a needleloom;
fabricating a tightly woven screen of polyester and cotton fibres;
locating the screen between the needle-punched fibre batts to form a composite structure in which the screen forms an inner layer between the two fibre batts; and
needle-punching the composite structure on a needleloom to produce a single, layered fabric body in a needle-punching process in which the punching density is about 1700-1900 punches per square cm.
Preferably, the punching density will be about 1800 punches per square cm.
The method may include the further step of securing a liquid permeable layer, which is substantially non-adherent to human or animal tissue, to at least one side of the layered fabric body.
The needle-punched fibre batts may be of porous polyester. The screen may be fabricated of 80% polyester and 20% cotton yarns. It may be fabricated to have a thread density of about 120 to 150 threads per square inch. It may be fabricated to have a yarn count of about 32 to 40. It may be fabricated to have a weight per unit area of approximately 100 g/m2.
The composite structure may be needle-punched to produce a single layered fabric body having a mass of about 700-750 g/m2. The needle punching process may be repeated according to the thickness or effect desired. The composite structure may be needle-punched so that the thickness of the single layered fabric body will typically be not more than about 3 mm.
The fibre batts may have a fineness of about 1.5 denier. They may be fabricated to have a weight per unit area of approximately 300 g/m2.
The liquid permeable layer may be of foraminous or perforated synthetic polymeric material. It may be selected from xe2x80x9cMYLARxe2x80x9d (trade name) and xe2x80x9cTELFAxe2x80x9d (trade name).
Securing the liquid permeable layer to the at least one side of the layered fabric body may be achieved by heat treatment under pressure.
The invention extends to a method of removing exudate from a wound, the method including the step of applying to an exudating wound at least one wound dressing as hereinbefore described.